Retroreflective Temperature- and Pressure-Sensitive Paints

The retroreflective-enhanced system combines PSP/TSP with specially treated glass microspheres to enable simultaneous surface and flow field measurements. The process involves a multi-layer coating system including primer, epoxy base coat, and acrylic polymer/ceramic binder, with microspheres applied while the binder retains adhesive properties. The glass microspheres may be uncoated, half-coated with aluminum, or pre-processed to be coated in another chemical. The system leverages dual optical characteristics: the underlying PSP/TSP responds to pressure and temperature changes through luminescence intensity variations at specific wavelengths, while embedded microspheres provide retroreflective properties enabling focused SAFS, shadowgraph, or BOS visualization techniques. This configuration allows simultaneous capture of on-body surface measurements and off-body flow field disturbances. The invention enables measurements from a single viewing orientation rather than requiring orthogonal optical access points. While specific excitation lighting, wavelength filtering, and camera positioning are still necessary, the system significantly streamlines experimental setup compared to traditional separate approaches. While initially developed for aerodynamic testing and flow visualization research, this invention supports optical measurement and surface analysis applications. By enabling simultaneous measurements from a single optical access point, the retroreflective-enhanced PSP/TSP offers a streamlined solution for systems where optical access limitations are critical. The system is a TRL 6, having undergone successful validation in wind tunnel testing, and is available for patent licensing. Pressure-sensitive paints (PSP) and temperature-sensitive paints (TSP) are widely used for surface measurement and flow visualization, yet their application prevents simultaneous schlieren-based visualization as the model on which they're applied obstructs schlieren line-of-sight and has separate optical access and alignment requirements. By making PSP/TSP surfaces exhibit retroreflective properties, methods such as self-aligned focusing schieren (SAFS), background-oriented schlieren (BOS), and shadowgraph could leverage the surface to provide a simultaneous off-body flow visualization capability. However, achieving desired accuracy, optical clarity, and retroreflective properties within conventional PSP systems depends on coating composition, surface preparation, and optical properties. This restricts flexibility in obtaining simultaneous on-body surface measurements and off-body flow visualization. To address these limitations, researchers at NASA Langley Research Center developed Retroreflective-Enhanced PSP/TSPs for Simultaneous Schlieren-Based Measurements. This solution enables simultaneous acquisition of surface measurements and schlieren imagery from a single optical access point across wider aerodynamic testing scenarios. The retroreflective-enhanced PSP/TSP enhances combined surface and flow field measurements with improved optical efficiency, making it a versatile tool for comprehensive aerodynamic testing and flow visualization.